Lymphocytes from patients suffering from AIDS or AIDS Related Complex (ARC) have been evaluated for surface phenotype changes during the course of their disease. In all cases a subpopulation of helper T Lymphocyte (the inducer of cytotoxic/suppressor cells, Leu 8) has been shown to selectively be depleted from peripheral blood of these patients. Further studies are underway to better characterize the nature of this subpopulation loss. Heterologous antisera as well as monoclonal antibodies to the AIDS virus are being prepared and will be used as a surface probe to define by two and three color FACS analysis the cells which are infected. Two color quantitative isolation of the antibody positive cells can then be analyzed with DNA probes made from the AIDS virus to determine if these cells bear proviral DNA.